This invention relates to a synchronizing indicator for indicating the approach to equality of speeds of two rotary devices.
It's primary use is thought to be for synchronizing the rotation speeds of twin engined ships or aircraft, although it may be used to synchronize any two rotary devices which may be each equipped to produce a set of signals from which may be derived pulses having a rate proportional to their respective speeds of operation.
By `synchronization` herein is intended the meaning that the twin rotary devices may be controlled to bring their speeds toward equality within design limits as hereinafter described. `Synchronization` does not, in this application, imply the kind of precision required to mesh the gears of two rotating machines.
In the past, methods of synchronization of two rotary devices have used a pair of lamps to indicate which device is rotating faster than the other. However with such a display, the resultant attempts to equalize the speed tend to result in overshooting. Where a third lamp is employed to indicate that the rotary speeds of the two devices are within a design synchronization range, the operator has no way of knowing when the engines are close to the limits of the synchronization range so that there frequently results a flashing between the lamps.